In recent years, the application of the so-called optical interconnection is widespread as the technology for transmitting signals at high speed in a system device, between system devices or between optical modules. The optical interconnection is the technique that treats an optical component like an electrical component, and allows the optical component to be implemented in a motherboard or a circuit board used in a personal computer, a vehicle or an optical transceiver.
The optical module for use in such optical interconnection has a variety of applications such as an internal connection of the media converter and switching hub, as well as component connection in a device or between devices (e.g., optical transceivers, medical equipment, test equipment, video system, and high-speed computer cluster).
There is an increasing demand for an lens array, in which a plurality of small-diameter lenses are arranged, as an optical component which is applied to the above-mentioned type of optical module. The lens array may be able to realize a compact structure for multichannel optical communications.
Conventionally, a photoelectric conversion device equipped with a plurality of light emitting elements (for example, VCSEL: Vertical Cavity Surface Emitting Laser) can be attached (or coupled) to the lens array, and a plurality of optical fibers can be coupled to the lens array as optical transmission medium.
With the photoelectric conversion device and the optical fibers being coupled to the lens array, the lens array can optically connect (couple) the light emitted from the light emitting elements of the photoelectric conversion device to the ends of the optical fibers respectively to perform multichannel optical transmissions.
Conventionally, in the optical communication using an optical fiber (or optical fibers), it is required to attenuate an amount of light coupled into the optical fiber for the reasons of communication standard and safety. Such requirement is also applied to the lens array.
Patent Literature 1 (Japanese Patent No. 4644218) and Patent Literature 2 (PCT International Publication No. WO 2010/050183 A1) disclose the technique to cause the two optical connectors to abut onto each other, with an adhesive connecting member being interposed, and connect these optical connectors by means of the adhesiveness of the adhesive connecting member. More specifically, the technique of Patent Literature 1 (Japanese Patent No. 4644218) and Patent Literature 2 (PCT International Publication No. WO 2010/050183 A1) prepares a jig for adhering the adhesive connecting member. The jig has an insertion hole, and a detachment film and the adhesive connecting member are stacked on a bottom face of the insertion hole. The optical connector is inserted into the insertion hole of the jig, and the front end face of the connector is joined to the adhesive connecting member by means of its adhesiveness. Upon pulling out the optical connector from the insertion hole, the adhesive connecting member that is now attached to the optical connector is peeled (detached) from the detachment film. In this manner, the optical connector having a front end face to which the adhesive connecting member is attached is caused to abut onto the mating optical connector to couple the two optical connectors. A stress generated upon the abutting can cause the adhesive connecting member to appropriately attach (adhere) between the two optical connectors, without adhesion failure such as wrinkles, bubbles, rolling up, and floating.
If the technique disclosed in Patent Literature 1 (Japanese Patent No. 4644218) and Patent Literature 2 (PCT International Publication No. WO 2010/050183 A1) is applied to an adhesive light attenuation film to attach the light attenuation film to a given lens array, it can be expected that a particular optical feature (optical attenuation in this specification) is imparted to the lens array at low cost.